[Means for Solving the Problem] In a current switch circuit A used for a current steering D/A converter, a current switch basic circuit 1 includes first and second transistors Tr121 and Tr122 included in a differential switch 12. A threshold voltage control circuit 5 has an output terminal Vbout controlling the substrate voltage to be outputted to the substrate terminal of each of the two transistors Tr121 and Tr122 included in the differential switch 12 for controlling the threshold voltage of the two transistors of the differential switch. Accordingly, the present invention improves the decrease in the dynamic range of the current switch basic circuit 1 dependent on the threshold of each of the two transistors in the differential switch 12 and realizes a wider output voltage range without causing deterioration in properties even in a case that the power voltage is reduced in the current switch basic circuit 1.